COMPONENT OPERATION / Pump Device REGULATOR FOR MAIN PUMP The regulators are provided on the top of main pumps and control the pump delivery flow rate. Pump delivery flow rate is controlled as flow rate control pressure from pump control solenoid valve (4) increases or decreases. Self pump delivery pressure P1 is routed to spool (2) through check valve (6) and acts on spool (2). Main pump delivery pressure P1 is also routed into the small chamber of servo piston (11) all the time. As pump control solenoid valve (4) is activated, servo assist pressure Psv from the pilot pump is reduced and acts on pilot piston (3) as flow rate control pres- sure.
Also, servo assist pressure Psv is combined with self pump delivery pressure P1 through check valve (5). 5 To Control Valve Psv 4 6 7 3 8 9 2 10 1 P1 T1J1-03-01-004 Pilot Pump 11 Main Pump T3-1-4